Make GenerateAntlrGrammar task cacheable
Make GenerateAntlrGrammar task cacheable

Test: ./gradlew room:room-compiler:generateAntlrGrammar
Change-Id: I19457492606676a5f9fda3f2508422ce69d244e6

AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx